how small of a grow room?, i have 2 plants each one with a 150 hps on them, what i did is make a box for each plant out of plywood the exact size it needed to be for the plant at full growth that way there is no wasted light. then covered the walls with aluminium foil (dull side out to prevent burn spots). It works good but im gonna put a couple low power flouro's on the sides of the plants for extra light on the lower leaves